https://romanticdeveloper.tistory.com/58
object-fit : cover https://multifidus.tistory.com/182
https://velog.io/@suld2495/display-flex-%EC%86%8D%EC%84%B1-%EC%9E%90%EC%8B%9D%EC%9A%94%EC%86%8C-%EC%9A%B0%EC%B8%A1-%EC%A0%95%EB%A0%AC
classList 사용 https://sisiblog.tistory.com/234
